BIOSTATISTICS CORE ? CORE F: PROJECT SUMMARY/ABSTRACT The BIOCARD study is a longitudinal, observational study of 349 individuals who were cognitively normal and primarily middle aged (mean age=57.1) at enrollment. The subjects have now been followed for up to 27 years. The overall objectives of the project are to further advance the study of preclinical Alzheimer?s disease by: (1) clarifying the pattern and rate of change in AD biomarkers (including those based on CSF, blood, MRI, and PET imaging) and cognition; the biomarkers to be studied include several promising novel biomarkers derived from blood, CSF and brain imaging. (2) maximizing our data by working collaboratively with several research groups who have comparable data, and (3) providing a publicly accessible data, brain scans, and biological specimens, for researchers in the field. To accomplish these goals we established 7 Cores and, with this application, are also including 2 projects. The Biostatistics Core (Core F) is responsible for overseeing the study design and statistical analyses related to the BIOCARD study. The specific aims include: (1) to provide statistical support and expert statistical consultation for all analyses associated with the study, (2) to adopt and develop statistical methods and analytical tools to study biomarkers associated with the preclinical phase of Alzheimer?s disease, (3) to design and identify proper and robust analytical approaches to analyze integrated data from across the Cores and Projects, (4) to provide power calculations, sample size estimates and other quantitative approaches to examining new biomarkers that might be identified during the coming funding cycle, and (5) to incorporate newly developed measures, such as composite scores, into the datafiles shared with external investigators.